From about 8 weeks of pregnancy the uterus begins to generate small waves of contractions. These are known as Braxton-Hicks contractions (after the person who named them).
Braxton-Hicks contractions are usually painless, however some women find them quite painful, particularly in the last half of their pregnancy. The uterus is a large group of muscles and Braxton-Hicks contractions are a way of toning these muscles as well as stimulating your unborn baby. Every time your baby feels the uterus tightening around them, it helps to stimulate their circulation, similar to a massage.
Women often describe Braxton-Hicks contractions as a tightness or hardness or a slight cramping of their belly. Some liken it to a tight band pulling on their uterus which usually stops if they change what they are doing. For example, if you have been walking and you feel a Braxton-Hicks contraction, sometimes when you stop so does the contraction.
Many women, especially first time mothers, are not aware of their Braxton-Hicks contractions, unless their caregiver points one out to them during an examination of their pregnant belly. Other women, especially second and third time mothers, notice them from about half way through their pregnancy and can find them uncomfortable or perhaps painful, even labour-like.
Braxton-Hicks contractions are NOT a sign of prelabour or labour, but can be confused with prelabour at times. Unlike prelabour the contractions are generally sporadic or irregular and rarely less than 5-10 minutes apart. Braxton-Hicks contractions do not thin or open (dilate) your cervix.
Note: If you are less than 37 weeks pregnant and you are getting painful or cramping, contraction sensations every 15 minutes or less, it is advisable to contact your caregiver. This is to rule out premature labour and confirm that they are indeed Braxton-Hicks contractions.